My download speeds have for some reason, plummeted to a dragging pace. The other day I was downloading a file, and it was going at around
500 bytes per minute. It hasn't always been this way, here's a speed test from last October.

Here's one from yesterday.
Now, I know this is a
very broad question, but these speed will NOT do for a music collector.
Is there any way I can diagnose this problem and possibly fix it? My internet connection speed is fine (albeit, somewhat sluggish), it's just the download speed.
Also, I'm not sure if this is a related issue, but videos have also been loading at an unusable rate. Here's a chart:
Any help at all would be appreciated guys, thanks.